Trouble keeping iron tip clean

[cloudscapes]

For all the years I've amassed throwing parts together, painting pretty boxes and designing effects some would consider really complex, I still cannot keep my iron tip from oxidizing after a few hours of use before it's nearly useless. And I've had enough of it.

This is what I do when I buy a new tip for my Weller WES51. Before heating it up for the first time, I do the wrap-around trick with lead-free rosin core solder. 1mm thick, 96.5Sn/3Ag/.5Cu. With the solder coiled around the new tip, I power it on at around 700F and let the solder bond to the tip, ie tinning. It looks perfect! But it doesn't last. After a few (literally less than a dozen) cycles of soldering a couple components, wiping the tip with either a wet sponge or steel curly stuff, protecting/retinning it with tip tinner made for the job, and after a half hour I can already no longer "wet" solder on the tip properly. It becomes patchy/oxidized in places, no matter how I clean it. I never sand or scrape the tin clean, as I know not to damage the thin plating.

A couple hours shelf life per tip is not normal, and obviously it's something I'm doing very wrong. I know other people use the same tip for hundreds of hours. Yet from what I can tell, I'm doing everything by the book. Properly tin it when using it the first time, retin it every time I'm done for a session (which, after an hours work, like I said, is nowhere near as good as the first tinning).

The "solution" of completely retinning the tip every minute you put the iron done is wrong, obviously, since I'd be using 10 times more solder just to tin than I do on components. So that's not it.

[greaser_au]

I only ever had problems as described here on the variable-temperature irons when the temperature was left on higher settings - or if the tip was abused e.g. 'drilling' holes in plastic...  The usual advice is to leave a decent blob of solder on the tip if not soldering for a few minutes.

Note: I have no experience with lead-free solder in general use, I just used to get all the 'foregn orders' e.g soldering the girls' jewellery etc. and we had some around for that - and that is where the variable temp iron - or a #8 tip - was used!

david

[Rob Strand]

It could be the brand of solder you are using.  The flux might be causing the problem.

Interesting to find this (the comments in the text more than the product),
http://www.eis-inc.com/files/pdf/supplier_showcase_page_downloads/weller/renewing_an_oxidized_soldering_tip.pdf

I have to say I've have a lot less problem in general with the slightly larger chisel tips compared to the small pointy tips that are supplied with modern irons - where you often have to bump the temperature.  (Except for one iron which was an expensive temperature controlled unit with rapid heating which seemed to work fine with all sorts of tips.)

I also had a case where the iron was touching the holder in a way which removed heat when the iron was in the holder.  As a result you would have to crank them temperature but then it would be too high after soldering a while.  It caused all sorts of grief until I worked out what was going on.

[Jdansti]

I don't have experience with lead-free either, but I've found that coating the tip with a big glob of solder right before I turn the iron off protects it from oxidation. Doing this, I've had tips last many years.

Edit: By cycles, it sounds like you might mean that you can't wet the tip after making a dozen or so solder joints with a brand new tip. I would try not ramping up to 700 to tin the tip. Just bring it up to just under 400, tin the tip, and start soldering and see what happens.

According to Hakko, you'll go through tips faster with lead-free solder due to the higher melting point, but it seems you're going through them way faster than normal.

From Hakko:
(https://www.hakko.com/english/lead_free/pages/)

In general, the melting point of lead-free solder is 20℃ to 45℃ higher than conventional eutectic solder. (A popular type contains approximately 40% lead.)

Assume, for example, that a soldering iron is set to a temperature of 340℃ to use eutectic solder (Sn-Pb). If the eutectic solder is replaced with lead-free solder (Sn-0.7Cu), the soldering iron must be set to around 380℃, which is close to the maximum temperature for soldering. Such a high temperature also causes shorter tip life (due to oxidation or erosion), carbonization of the flux in the solder, and splashing of the flux and solder. (It is said that using lead-free solder decreases the tip life by 4 to 5 times compared with eutectic solder.)

As well, many recently-developed devices are heat-sensitive. There are cases in which the high melting point affects not only the iron tips but also devices and P.W.B.

Then, in actual use, what problems are occurring at the site of soldering?
Soldering problems reported after the change to lead-free solder are:
・Feeding of improper amount of solder
・Overheating and cracking
・Solder coming off
・Resin joint or protrusion icicle
・Bridging

Moreover, additional cost is required because iron tips must be replaced more frequently.

[antonis]

Just try to use the biggest convenient tip with the lowest convenient temperature..

I've destroyed some fine tips because I was too lazy to wait for cooling and tip change between PCB and jack lug soldering..

[Mark Hammer]

I have no idea where the recommendation to wipe with a wet sponge came from, nor what keeps the advice alive all these years.

I used to use the sponge that came with the kit (including the iron, stand, and little curly coil of solder) and would go through a tip seemingly every 6 months or so (and bear in mind I'm not soldering every day).  The ends would quickly erode and I would try tricks like the OP described.  I bought tinning paste, and was constantly retinning the tips, but to no avail.  They would all progressively disappear before my eyes.  I followed up on a suggestion to use the cheap brass/copper curly scrub pads (like those shown) and have been using the same tip for the last 5-6 years, with no visible signs of wearing down.  Hakko and others will sell a tip-cleaning pad for $9 or something, but the 3-for-$1 scrub pads from the dollar store work just fine.

Switch from wet to curly and you'll be glad you did.

[cloudscapes]

Thanks for the info guys, I'll write up a more proper reply later.

I use a wet sponge because so many articles and videos tell me to use a wet sponge. Because I have no formal training in electronics, I'm at the mercy of information I can find, as long as it's said by people who sound like they know what they're talking about.

Similarly, I've also found a number of videos and articles that recommend *sanding* the tip to "renew" it, where I know that to be very bad advice. So I guess it's my own fault.  I'll ditch the wet sponge. I had already been using the curly metal pad so I'll stick with that.

Applying solder to the tip before it heats up each time? I'll try that, though the way I'd been going through tips, any "second time" I heat up the tip will never have the same ability to be tinned as the first time I initially tin it.

I'll lower the temperature of the iron, it's almost always at 700F. I forget where I read that was the ideal temperature.

The chisel tip I almost always use is .093"x.020"x.625". I know it's small, but it's as big as I'll go since I often do a lot of SMD work, often very fine pitch SMD work. I also occasionally use conical tips.

Excuse me while I go order some new tips (again)....

[John Lyons]

I use a hakko iron and had bought some new tips.
After a few wipes on the brass pad the tip would not stay
clean. I switched to NEW wet sponge and that was worse
by far. I'd never had problems with this so I was perplexed.
On a hunch I pulled out the sponge and rinsed it out thoroughly
a few times. Then it worked perfectly keeping the iron clean.
There must have been something in the sponge reacting with the
heat to prevent the tip from keeping clean.

I agree that the dollar store "Brass" sponges can work but I have
gone back to a wet (well rinsed out) sponge.

[rutabaga bob]

I bought a new Aoyue soldering station after my Radio Shack 35-watter ran out of replacement tips.  The tip has never really tinned properly - the solder always sits in a blob.  I use a well-rinsed square of sponge that I wet and wring out often, but it hasn't been successful like John has found.  I'm assuming it must be the material the tip is made of.  Next try is the curly metal thing.

[anotherjim]

700F, that's 371C. Not excessive. Mine is running at 400C.
I have always been a wet sponge man myself. Not noticed any particular problems with my tip from doing this. That said, I've never used other than 60:40 rosin core solder. I have no doubt this fancy new un-leaded brings different conditions.

[vigilante397]

I use a Weller WESD51 (pretty much the same as your iron) that I got for Christmas in 2013, and the tip that came with it is still going! If you're buying actual Weller tips, changing super often will get expensive fast. But I agree, 700F is a reasonable temperature, I usually keep mine there as well.

The only thing I really do different is, like everyone else said, solder. I have never used lead free, I always use 60/40 rosin core. Also agree with everyone else, curly stuff, no sponges. I have another iron I keep at work that's a lot cheaper and the tip oxidizes quite a bit, but original Weller tips are legit if you take care of them.

[Rob Strand]

This is a very good article,

http://www.elexp.com/Images/Weller_Coping_with_Lead_Free.pdf

p16:      iron layer  thickness; 
            (cheap tips might have a thinner layer and reduced life)

p21:      PbF solders vs lifetime
            ( no data on 96.5Sn/3Ag/0.5Cu vs  95.8Sn/3.5Ag/0.7Cu.)

p22:     temperature vs lifetime
           Clearly small changes in tip temp have a significant effect!

p29:   Summary

p30:  comments on dry vs wet cleaning

Note Larger chisel tips have somewhat better heat transfer.  This should let you set the iron temp lower and hence increase life.     Also the soldering technique of melting the solder first on the tip then flowing it over the joint ensures good heat transfer and will let you set the iron temp lower.

[Rob Strand]

I have no idea where the recommendation to wipe with a wet sponge came from, nor what keeps the advice alive all these years.

Apparently, the mixed advice on Wet vs Dry cleaning is a result of the leaded to lead-free transition.   Where wet (actually damp) sponges were OK for leaded the industry has gradually discovered that dry cleaning is better for lead-free.

[Jdansti]

This is a very good article,

http://www.elexp.com/Images/Weller_Coping_with_Lead_Free.pdf

p16:      iron layer  thickness; 
            (cheap tips might have a thinner layer and reduced life)

p21:      PbF solders vs lifetime
            ( no data on 96.5Sn/3Ag/0.5Cu vs  95.8Sn/3.5Ag/0.7Cu.)

p22:     temperature vs lifetime
           Clearly small changes in tip temp have a significant effect!

p29:   Summary

p30:  comments on dry vs wet cleaning

Note Larger chisel tips have somewhat better heat transfer.  This should let you set the iron temp lower and hence increase life.     Also the soldering technique of melting the solder first on the tip then flowing it over the joint ensures good heat transfer and will let you set the iron temp lower.

From your link:



I wonder if Cloudscapes is getting false temperature readings and it's really hotter than he thinks.
 

[Rob Strand]

I wonder if Cloudscapes is getting false temperature readings and it's really hotter than he thinks.

Very true.  Sometimes the things we assume are true are the real problem!

For medical devices we actually have to verify the soldering iron tip temperature.

[Jdansti]

I wonder if Cloudscapes is getting false temperature readings and it's really hotter than he thinks.

Very true.  Sometimes the things we assume are true are the real problem!

For medical devices we actually have to verify the soldering iron tip temperature.

How do you do that? Thermocouple?

[greaser_au]

How do you do that? Thermocouple?

A TC probe is one method - I have used this  (and some multimeters directly support the  attachment)...  There are also dedicated testers like the Hakko 191 or FG100/101. 

Ongoing calibration is a potential problem, though, the probe is damaged by repeated tests with solder/flux.

david

[Rob Strand]

How do you do that? Thermocouple?

Yes but you need to minimize heat loss.  We used to clean the tip, create a ball of solder, apply the probe, wait for it to stabilize, then measure.   The ball is isolated so there is minimal heat loss.  Some heat still escapes through the thermocouple leads.   IIRC the dedicated testers greaser_au mentioned have a small solder well which they try to isolate.  I don't know if they compensate for the loss in the well mountings.

To put things in perspective the temperature sensor in many temperature controlled irons is in the reservoir.  The tip temp is usually close if the iron is just sitting there.  However if you have a fine tip and put it on the work the temperature will drop quite a bit.  The normal thing is to jack-up the temperature.  The larger tips reduce this problem.

[PRR]

> Applying solder to the tip before it heats up each time?

No; apply flux-core solder to the tip WHILE it heats-up. You need to -minimize- the time the bare tip is exposed to air while hot.

I sniff it, and start poking solder at it as soon as it will melt. I want a good cloud of flux-smoke.

After every joint, and every bang to remove excess solder, I solder-up again. Does not take much, if you do it often.

I've had wet sponges and had mixed results. The Weller paper cites mineral deposits, which makes much sense. It would not take much 'lime' to repel solder. The water here has iron-bugs which would probably eat the solder or the tip?

[crey]

I used to have the same issue due to a slightly higher temp being used, but roughly a year ago I went to the little tins of Tip Tinner and the brass "sponge".
The current pencil tip has been used for about 6 months now, where I used to go through at least 3 in that some timeframe.
I accidentally left it on overnight once, and the next morning I thought the tip was toast, I simply ran it through the brass a few times and put the tinner on it, as good as new.
As far as "wet vs dry", I personally never liked how sponging the tip cooled it off.. so... At least running it through the brass doesn't affect the heat per se.